1. Technical Field of the Invention
The present invention relates generally to mine tunnel supports and more specifically to a method and device for moving a shield-type support trestle.
2. Discussion of the Related Art
Shield-type support trestles are often employed to support roofs of mine tunnels. The trestles have stamps arranged between a roof pressure cap and a lying skid for providing support to the roof. A pushing ram is provided in the lying skid to allow the trestle to move within the tunnel.
It is known to move such a trestle under load or partial load. The set shield-type support trestle is first partially depressurized and then moved under partial load. After this move is completed, the shield-type support trestle is positioned again with full load. This known movement under a partial load is accomplished with a constant distance between roof pressure cap and lying skid. Accordingly, this moving process is only possible when the roof and the bottom run fairly parallel to each other, so that the shield-type support trestle retains firm contact with the tunnel roof and the roof is not damaged because of excessive resistance during moving. Therefore, this current method is not adaptable to varying surface conditions encountered by the lying skid.
Accordingly, it is an object of the present invention to provide a method and device for moving a shield-type support trestle which both provides sufficient support force to the roof during the moving process and sufficiently protects the roof independently of existing topographical conditions of the tunnel.
Additional objects and advantages of the present invention will become apparent from the drawings and description which follow.